THE BACILLUS OF LEPROSY. 269 



delicate, but in the older lesions may be very dense. Periarteritis 

 is a common change, and very frequently the superficial nerves 

 become involved in the nodules and undergo atrophy. The 

 tissue in the leprous lesions is comparatively vascular, at least 

 when young, and, unlike tubercular lesions, never shows casea- 

 tion. Some of the lepra cells may contain several nuclei, but 

 we do not meet with cells resembling in their appearance tuber- 

 cle giant-cells, nor does an arrangement like that in tubercle 

 follicles occur. 



In the ancesthetic form the lesion of the nerves is the out- 

 standing feature. These are the seat of diffuse infiltrations which 

 lead to the destruction of the nerve fibres. In the earlier stages, 

 in which the chief symptoms are pains along the nerves, there 

 occur patches on the skin, often of considerable size, the margins 

 of which show a somewhat livid congestion. Later, these patches 

 become pale in the central parts, and the periphery becomes 

 pigmented. There then follow remarkable series of trophic dis- 

 turbances in which the skin, muscles, and bones are especially 

 involved. The skin often becomes atrophied, parchment-like, 

 and anaesthetic ; frequently pemphigoid bullae or other skin 

 eruptions occur. The bones become atrophied, and, owing to 

 the irregular affection of the muscles, great distortion of the 

 extremities may result. Partly owing to injury to which the feet 

 and arms are liable from their anaesthetic condition, and partly 

 owing to trophic disturbances, necrosis and separation of parts are 

 liable to occur. In this way great distortion results. The lesions 

 in the nerves are of the same nature as those described above, 

 that is, they are the result of a chronic inflammatory process, 

 but the granulation tissue is less in amount, and has a greater 

 tendency to undergo cicatricial contraction. This is to be 

 associated with the fact that the bacilli are present in fewer 

 numbers. 



Bacillus of Leprosy. This bacillus was first observed in 

 leprous tissues by Hansen in 1871, and was the subject of several 

 communications by him in 1874 and later. Further researches, 

 first by Neisser in 1879, and afterwards by observers in various 

 parts of the world, agreed in their main results, and confirmed 

 the accuracy of Hansen's observations. The bacilli as seen in 

 scrapings of ulcerated leprous nodules, or in sections, have the 

 following characters. They are thin rods of practically the same 



